Investments - Investments in Variable Interest Entities (Detail) - USD ($) |
Dec. 31, 2019 |
Dec. 31, 2018 |
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Variable Interest Entity [Line Items] | ||||
Maximum Exposure to Loss | $ 2,800,000 | $ 2,100,000 | ||
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member] | ||||
Variable Interest Entity [Line Items] | ||||
Investment | [1] | 4,699,000 | 3,899,000 | |
Maximum Exposure to Loss | [1] | $ 5,679,000 | $ 4,879,000 | |
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